The present invention relates to a bearing device for threaded spindles by which axial movement of the spindle is eliminated.
Threaded spindles are employed in machine tools, measuring installations and electronic reproduction technology for the movement of supports, and the like, where high precision is required. However, even when the transport spindle is very precisely machined, the support movement periodically exhibits small path errors due to small axial dislocations of the spindle which arise from unavoidable imprecisions in the spindle bearings. This is true even when high precision rolling bearings (i.e., ball bearings, roller bearings, etc.) are used. Furthermore, these path errors are often unacceptable.
In such situations it is common to machine an inside cone in one end face of the spindle. This inside cone is machined with the spindle threads in one machining step. Using this cone, the spindle is seated against a stationary lathe center. An axially-movable, spring-loaded bearing at the end of the spindle, opposite the inside cone, constantly presses the spindle and inside cone against the lathe center.
However, this bearing arrangement may fail when the transport spindle is very long or thick, and thus, heavy. Specifically, excessively high planar pressures occur at the lathe center and lubricating problems result.
As a result of imprecisions in the rolling bearing in which it is seated, the lathe center will also introduce axial movements into the spindle.
Large spindles are mounted in rolling bearings with the aid of step bearings. Then, however, the lathe center point is unavailable as a reference bearing.
It is therefore an object of this invention to provide a bearing device for threaded spindles which eliminates axial dislocations of the spindle and provides for a reference bearing.
These and other objects of this invention will become apparent from the following description and appended claims.